Different Types of Regulators
There are different type of regulators / Self Actuated Pressure Control Valves as per below.
DOWNSTREAM PRESSURE CONTROL VALVES (Pressure Regulators / Pressure Reducing Valves) : Self-Actuated Pressure Control Valves, which control pressure at its outlet, are known as Self actuated downstream pressure control valves /Pressure Reducing Valves / Pressure Regulators. These valves regulate its outlet pressure near to the desired set point, irrespective of variation in flow through the valve and variation in inlet pressure.
UPSTREAM PRESSURE CONTROL VALVES (Back Pressure Regulators) : Self-Actuated Pressure Control Valves, which control pressure at its inlet, are known as Self actuated upstream pressure control valves / Pressure Relieving Regulators / Back Pressure Regulating Valves. These valves regulate its inlet pressure near to the desired set point, by opening in proportion to the rise in inlet pressure above set point. These proportional type regulating valves and application they serve are very different from conventional safety relief valves; which protect the pipe line or equipment from over pressure by popping open. Safety Relief Valves are not meant for continuous proportional control action.
For both Upstream & downstream Pressure Control Valves, Direct acting as well as pilot operated valves is available.
DIRECT ACTING VALVE : In Direct acting valve, typically a spring Diaphragm actuator is used to control the valve opening. On one side of the Diaphragm, controlled pressure is acting and on another spring force is applied.
In case of downstream pressure control valve, spring exerts valve opening force and downstream pressure acting on another side of diaphragm exerts valve closing force. When controlled downstream pressure reduces below set pressure, valve opens due to unbalanced spring force. Whereas in case of upstream pressure control valve, spring exerts valve closing force to keep the valve in closed position and controlled upstream pressure exerts valve opening force on other side of diaphragm, which opens the valve when upstream pressure rises above set pressure.
PILOT OPERATED VALVE : In case of Pilot operated valve, a pilot Mechanism senses the controlled pressure and generates the motorising differential pressure across two sides of main valve Diaphragm to adjust the valve opening.
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